Open AIR Mini

The Open AIR Mini is an open-source ventilation controller designed to bring smart home control to mechanical ventilation units commonly found in European homes. Built around an ESP32 microcontroller, it replaces or augments the factory controller in Ducobox Silent, Ducobox Focus, Ducobox Reno, and Orcon MVS-15xx ventilation systems, providing full WiFi connectivity and Home Assistant integration through ESPHome firmware.

The board features an onboard Mean Well AC-DC converter that powers the system directly from 230VAC mains, eliminating the need for external power supplies. It provides regulated 5V and 3.3V rails for sensors, a 3.3V supply for the ESP32, and a 10V reference output for motor speed control via a 0-10V PWM interface. Two sensor connectors support a variety of optional environmental sensors including the Sensirion SCD-4x for CO2 measurement, SHT-4x for temperature and humidity, SGP41 for VOC and NOx indices, and the legacy Senseair S8 CO2 sensor via UART. Five status LEDs monitor each power rail, while the ESP32 onboard LED indicates system health.

With full OTA update support and a built-in web server, the Open AIR Mini can operate autonomously in disconnected mode using humidity-based fan speed thresholds, or be fully orchestrated through Home Assistant automations. The hardware design files, including schematics, BOM, Gerber files, and 3D STEP models, are published under the GPL-3.0 license on GitHub, making it a truly open platform for demand-controlled ventilation.